How Can I Access JavaScript Object Properties Dynamically Using Their Names as Strings?

Accessing JavaScript Object Properties by Name as a String

When working with JavaScript objects, it is often necessary to access properties dynamically based on their names stored in a variable or returned from a function. Here's how to achieve this:

Using Bracket Notation

The preferred method for accessing properties using a variable is to use bracket notation:

function read_prop(obj, prop) {
    return obj[prop];
}

For example, to access the 'right' property of the given object:

var side = read_prop(columns, 'right');

This is equivalent to the dot notation:

var side = columns.right;

Nested Object Properties

To access properties of nested objects, use multiple brackets:

var cx = foo['c']['x'];

Undefined Properties

Accessing an undefined property will return 'undefined':

foo['c']['q'] === undefined; // true

Conclusion

Using bracket notation provides a flexible way to access JavaScript object properties by name as a string, whether it's a simple or nested property. It allows for more dynamic property access, especially when working with dynamic data or unknown property names.

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